Each year more than 30 million bladder catheters are inserted into more than 5 million patients in the United States. Catheterized subjects acquire bacteriuria at the rate of 5% per day and are at risk for catheter-associated urinary tract infection (CAUTI) and bacteremia. The catheter-associated biofilm of adherent organisms plus secreted polysaccharide matrix is central to the pathogenesis of CAUTI. Organisms in biofilms have reduced susceptibility to antimicrobial agents and to host defenses compared to their planktonic counterparts. Thus, using standard antimicrobial agents to prevent CAUTI frequently leads to bladder colonization with resistant flora. E. coli, the most common causative agent of CAUTI, has been used as a model organism to study biofilm formation in vitro. However, biofilm formation has not previously been studied on urinary catheters in human bladders. The specific aims of this project are (1) to determine whether genes described as essential to bio- film formation by E. coli in vitro are expressed in vivo by E. coli 83972 (a nonvirulent strain) on the surface of urinary catheters dwelling in human bladders, and (2) to perform a clinical trial to determine whether deleting the genes identified in Aim 1 prevents E. coli from colonizing urinary catheters that are dwelling in human bladders. These studies will identify the genetic virulence factors of CAUTI which are potential targets for a new intervention called virulence factor modification. The concept of virulence factor modification, in which compounds are developed to inhibit virulence without killing the microorganism, is particularly attractive for prevention and treatment of CAUTI. Disarming pathogens by impairing their ability to form a biofilm in the bladder may impair their persistence and render them more susceptible to host defenses. Relevance of the proposed research to public health: CAUTI is an extremely common infection, one of the leading causes of nosocomial infection in the United States. CAUTI also interferes with the health and well-being of chronically catheterized populations. No effective strategy exists to prevent CAUTI in persons who require ongoing catheter use. Identifying genes that are required to cause CAUTI will lead to new strategies to prevent this illness. [unreadable] [unreadable] [unreadable]